ProxyInputStream


1   package hudson.remoting;
2   
3   import java.io.IOException  ;
4   import java.io.InputStream  ;
5   import java.io.OutputStream  ;
6   import java.io.Serializable  ;
7   
8   /**
9    * {@link InputStream} that reads bits from an exported
10   * {@link InputStream} on a remote machine.
11   *
12   * <p>
13   * TODO: pre-fetch bytes in advance
14   *
15   * @author Kohsuke Kawaguchi
16   */
17  final class ProxyInputStream extends InputStream   {
18      private Channel channel;
19      private int oid;
20  
21      /**
22       * Creates an already connected {@link ProxyOutputStream}.
23       *
24       * @param oid
25       *      The object id of the exported {@link OutputStream}.
26       */
27      public ProxyInputStream(Channel channel, int oid) throws IOException   {
28          this.channel = channel;
29          this.oid = oid;
30      }
31  
32      @Override  
33      public int read() throws IOException   {
34          try {
35              Buffer buf = new Chunk(oid, 1).call(channel);
36              if(buf.len==1)
37                  return buf.buf[0];
38              else
39                  return -1;
40          } catch (InterruptedException   e) {
41              // pretend EOF
42              Thread.currentThread().interrupt(); // process interrupt later
43              close();
44              return -1;
45          }
46      }
47  
48      @Override  
49      public int read(byte b[], int off, int len) throws IOException   {
50          try {
51              Buffer buf = new Chunk(oid,len).call(channel);
52              if(buf.len==-1) return -1;
53              System.arraycopy(buf.buf,0,b,off,buf.len);
54              return buf.len;
55          } catch (InterruptedException   e) {
56              // pretend EOF
57              Thread.currentThread().interrupt(); // process interrupt later
58              close();
59              return -1;
60          }
61      }
62  
63      @Override  
64      public synchronized void close() throws IOException   {
65          if(channel!=null) {
66              channel.send(new EOF(oid));
67              channel = null;
68              oid = -1;
69          }
70      }
71  
72      protected void finalize() throws Throwable   {
73          super.finalize();
74          close();
75      }
76  
77      private static final class Buffer implements Serializable   {
78          byte[] buf;
79          int len;
80  
81          public Buffer(int len) {
82              this.buf = new byte[len];
83          }
84  
85          public void read(InputStream   in) throws IOException   {
86              len = in.read(buf,0,buf.length);
87          }
88  
89          private static final long serialVersionUID = 1L;
90      }
91  
92      /**
93       * Command to fetch bytes.
94       */
95      private static final class Chunk extends Request<Buffer,IOException  > {
96          private final int oid;
97          private final int len;
98  
99          public Chunk(int oid, int len) {
100             this.oid = oid;
101             this.len = len;
102         }
103 
104         protected Buffer perform(Channel channel) throws IOException   {
105             InputStream   in = (InputStream  ) channel.getExportedObject(oid);
106 
107             Buffer buf = new Buffer(len);
108             buf.read(in);
109             return buf;
110         }
111     }
112 
113     /**
114      * {@link Command} for sending EOF.
115      */
116     private static final class EOF extends Command {
117         private final int oid;
118 
119         public EOF(int oid) {
120             this.oid = oid;
121         }
122 
123 
124         protected void execute(Channel channel) {
125             InputStream   in = (InputStream  ) channel.getExportedObject(oid);
126             channel.unexport(oid);
127             try {
128                 in.close();
129             } catch (IOException   e) {
130                 // ignore errors
131             }
132         }
133 
134         public String   toString() {
135             return "EOF("+oid+")";
136         }
137 
138         private static final long serialVersionUID = 1L;
139     }
140 }
141
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